SOME manufacturers do bolt-on upgrades to their vehicles. For example Dodge introduced a bolt-on upgrade to their SRT-4 Neon in 2003.

The kit comes with a modified engine management computer (the whole thing, not just the chip) along with high-flow fuel injectors. The nice thing about doing a factory upgrade is that you know for 100% certain that the parts are going to fit, and are going to work together with each other as well as your car. Since that original upgrade, Mopar have produced a veritable treasure trove of bolt-on upgrades for Dodge vehicles, and with most of them you can maintain some of the factory warranty.

Factory upgrades are starting to include chips too now, competing with the aftermarket chipping business. That was a move to counter the warranty problems that some kits caused.

Either way, factory bolt-ons are A Good Thing. If you want improved performance but are nervous about third-party products, getting something direct from Dodge, Ford, Toyota, and Mazda etc. is a good way to go. Think of your engine as a breathing machine. It needs to breathe in fuel and air, and it needs to breath out exhaust gasses. Anything that gets in the way of that process is going to impede its ability to breathe.

In reality of course, there are plenty of things in the way from air filters and flow sensors in the intake system, to catalysers and bizarre kinks and curves in the exhaust system. By eliminating or reducing these constrictions, you can allow your engine to breathe more easily.

Sort of like Nyquil or Night Nurse for an engine. By far the easiest and cheapest thing to start with is the air filter. From the factory, air filters are designed to be a compromise of filtering the guck out whilst letting the air through. Aftermarket manufacturers such as K&N and Jamex have been making high-flow air filters for years. The design of the filters is slightly different and they allow more air to pass through the filter whilst still stopping the majority of harmful particles. Again, like all these things, the claims of increased power can be hugely exaggerated.

In truth, simply changing the air filter will probably add another 2 or 3hp to your engine. More air going in more easily means the engine management system will adjust the fuelling accordingly and you’ll get a better fuel-air charge in the cylinder, resulting in a slight increase in power.Moving on a step from simply changing the filter, you can then start looking at intake upgrade kits, also known as cold air intake or induction kits (manufactured by companies such as Injen and AEM). The basic idea with these is to make the passage from the filter to the engine less convoluted. When air is forced to go around corners, it causes turbulence which slows down the flow.

By trying to make the intake pipes smoother and straighter, the idea is to give the air more chance to get to the engine and less chance of being screwed up in corners with turbulence. Cold-air kits normally remove the factory airbox from the car and poke the air intake into one of the front wings or right up front. The air in your engine bay is hot - really hot - and hot air is not conducive to good combustion.

By routing the intake to somewhere where it isn’t going to be sucking hot air from under the hood, you get cooler air going into your engine.

Because cooler air is denser, you can get a better fuel-air charge into the cylinder than you can by simply changing the stock air filter. Cold-air intake kits can add another 3 or 4hp of raw power to the engine but more often than not, you’ll notice an increase in torque lower down the rev range too.